Pumping unit with multiple intake ports



March 27, 1956 v E. s. WITCHGER PUMPING UNIT WITH MULTIPLE INTAKE PORTS Armmv y INVENTOR.

6 Sheets-Sheet l Filed Dec.

March 27, 1956 E. s. WITCHGER 2,739,538

PUMPING UNIT WITH MULTIPLE INTAKE PORTS Filed Dec. 14 1951 Sh r.s-Sheet 2 INVENTOR. fives/vs .5. Mrcwse-R Arron/v Y5 March 27, 1956 E. s. WITCHGER 8 PUMPING UNIT WITH MULTIPLE INTAKE PORTS Filed D80. 14, 1.951 6 Sheets-Sheet 3 l N V EN TOR. fl/GWE 5. Mir/nee Arra/g/veys March 27, 1956 E. s. WITCHGER 3 PUMPING UNIT WITH MULTIPLE INTAKE PORTS Filed Dec. 14, 1951 6 Sheets-Sheet 4 g INV NTOR.

@ 50 Ease/VEST lfCl/G'R 55 BY a I ,III '4 z I Armmvs ys March 27, 1956 s. WITCHGER 2,739,538

PUMPING UNIT WITH MULTIPLE INTAKE PORTS Filed Dec. 14, 1951 6 Sheets-Sheet 5 1/5 57 INVENTOR.

fawn/5. War/vase United States Patent PUMPING UNIT WITH MULTIPLE INTAKE PORTS Eugene S. Witchger, Grosse Pointe, Mich, assignor "to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application December I4, 1951, Serial No. 261,670

9 Claims. '(Cl. 103*126) This invention relates to fluid pumps and, more particularly, to rotary pumps of the meshing gear type.

In rotary pumps of this type, a rapid and noiseless filling of the pumping chambers is desirable and as one of its objects this invention provides a novel pump construction by which this is accomplished by a flow of fluid into the individual pumping chambers from opposite sides thereof simultaneously through correspondingly located intake ports, and wherein fluid supply means communicating with such intake ports maintains the same substantially filled with intake fluid.

Another object of this invention is to provide a novel pumping unit embodying a gear pump having double intake ports and a reservoir chamber located at an elevation above the intake .ports, and wherein one of the intake ports is connected with the reservoir chamber to be supplied with fluid therefrom and supply passage means adapted to contain fluid under pressure includes passages leading respectively to the reservoir chamber and to the other of said intake ports. I

Still another object is to provide a novel pumping unit of the character mentioned having rotor means driven by a hollow shaft and in which one of the air of intake ports is supplied with fluid through the hollow shaft.

A further object of this invention is to provide a novel rotary pump and shaft sealing means which includes a leakage chamber, and in which supply means adapted to supply intake fluid under pressure communicates with the leakage chamber for maintaining liquid therein.

Other objects and advantages of the invention will be apparent in the following detailed description and in the accompanying sheets of drawings in which:

Fig. l is a partial end elevation showing a pumping unit embodying the novel construction of the present invention;

Fig. 2 is a partial plan view of the pumping unit with r the reservoir thereof represented in construction lines only;

Fig. 3 is a vertical section taken through the gear .pump and reservoir substantially as indicated by section line 3-3 of Fig. 2;

Fig. 4 is a vertical section taken through the pump at a point adjacent the rotor chamber as indicated by section line 4-4 of Fig. 3 and showing the cooperating gear rotors;

Fig. 5 is another vertical section taken through the pump as indicated by section line 5-5 and showing one set of the intake and discharge ports;

Fig. 6 is a vertical section taken through the volume regulating valve means as indicated by section line 6-6 of Fig. 2;

Fig. 7 is a similar vertical section taken through the pressure regulating valve means as indicated by section line 77 of Fig. 2;

Fig. 8 is a partial end elevation similar to Fig. l but showing a modified form of pump unit;

Fig. 9 is a plan view of the modified pumping unit with the reservoir thereof shown in construction lines only;

2,739,538 Patented Mar. 27, 1956 Fig. 10 is another end elevation of the modified puinping unit but also showing portions of the unit in vertical section;

Fig. 11 is a vertical section taken through the modified pumping unit substantially on section line 11-11 of Fig. 10;

Fig. 12 is a vertical section taken through the by-p'ass valve means substantially as indicated by the irregular section line 12-12 of Fig. 9; and

Fig, 13 is a partial vertical section taken on section line 13-13 of Fig. 11 and showing the cooperating gear rotors.

In proceeding with a more detailed description of this invention, reference will first be made to the pumping unit 10 which is illustrated in Figs. 1 to 7 inclusive. The pumping unit here shown comprises in general a gear type rotary pump 11, a reservoir 12 mounted directly on the pump and a pair of fluid delivery and return conduits 13 and 14 which constitute a part of a closedloop external iluid circuit 15 with which the pump is connected. The pumping unit It can be used for various purposes and as one example thereof it can be used to operate a hydraulic power steering mechanism 16 of a motor vehicle. This hydraulic power steering mechanism is here shown only diagrammatically and is located in the external closed-loop fluid circuit 1'5.

The gear pump 11 is provided with a pump housing 17 comprising connected housing sections 17 and 1'7 of which the housing section 17 is the pump body and the housing section 17 is a cover for the pump body and is connected therewith by suitable belts or studs '18. The pump 11 is also provided with a rotor chamber 19 and a drive shaft 20 extending transversely through the rotor chamber. The inner end of the shaft 20 is rotatably supported in the housing section 17* by a suitable bushing 21 mounted therein. Theouter end of the shaft is rotatably supported in the housing section l7 by a suitable antifriction bearing 22 and is adapted to be connected with some available rotatable member from which the pump is to be driven. The housing section 17* is also provided with a mounting flange 23 by which the pump 11 is adapted to be connected with a suitable support.

A rotor means operable in the rotor chamber 19 comprises a pair of meshing gear members 24 and 25 which are rotatably driven by the shaft 20. The outer gear member 24 is a ring gear rotatably supported in the rotor chamber 19 by a bushing 26 mounted in the housing section 17 and the inner gear member 25 is mounted on the shaft 20 and connected therewith by a key 27. As is understood by persons skilled in this art, the coop crating portions of the outer and inner gear members 24 and 25 define a plurality of pumping chambers 28 therebetween of variable capacity and which extend transversely or axially of the rotor means.

For supplying fluid to the pumping chambers 28, the housing 17 is provided with double .intake ports, that is to say, a pair of arcuate intake ports 29 and 30 which are located on opposite sides of the rotor chamber 19. During rotation of the rotor means in the chamber 19, the pumpingchambers 28 are brought in succession into communication with the :paired intake ports 29 and 30. These intake ports communicate with the pumping chambers 28 from opposite sides thereof such that the filling of these chambers with intake fluid will be accomplished quickly and substantially without noise. When double intake ports are provided for the rotor means, such as the intake ports 29 and 30 here shown, the filling of the pumping chambers 28 can be accomplished with a lower linear velocity for'the intake fluid and hence a substantially complete and noiseless'filling of the pumping chain 3 bers will be consistently obtained even when the pump is operated at relatively high speeds.

The pump housing 17 is also provided with a pair of discharge ports 31 and 32 which are located on opposite sides of the rotor chamber and with which the pumping chambers 28 communicate in succession and deliver pumped fluid thereto under pressure. The discharge port 31 is in communication with the delivery conduit 13 through a valve chamber 33, to which further reference will presently be made, such that the pumped fluid being delivered by the rotor means will be supplied through the delivery conduit to the hydraulic steering mechanism 16 of the external fluid circuit 15. The fluid returning from the hydraulic steering mechanism 16 is delivered back to the pump housing 11 under pressure through the return conduit 14.

The reservoir 12 of the pumping unit comprises a shell or container 34 mounted directly on the pump hous ing 17 and containing a reservoir chamber 35 which is located at an elevation above the rotor chamber 19 and the intake ports 29 and 30. The shell 34 is here shown as comprising a cup-shaped member adapted to contain a quantity of fluid and having a suitable cover 36 thereon.

Passage means is provided in the pump housing 17 for supplying intake fluid to the intake ports 29 and 30. This passage means comprises a depending passage 37 extending downwardly from the reservoir chamber 35 and connecting the latter with the intake port 29 for supplying fluid to this intake port under the pressure of the fluid head in the reservoir chamber. The supply passage means for the intake port 30 comprises an axial passage 38 of the shaft which communicates with an annular chamber 39 of the housing section 17 through radial openings 40, and a short connecting passage 41 of the housing section 17 which connects the intake port with the annular chamber 39. At the outer end of the shaft 20, the axial passage 38 communicates with the return conduit 14 through the axial passage portion 42 of a branched supply passage 43 formed in the housing section 17 The branched supply passage 43 also includes a substantially vertical passage portion 44 which communicates with the reservoir chamber through the passage 45 of a coupling member 46.

A strainer 47 associated with the reservoir 12 is here shown as comprising a tubular screen supported in sur- 1 rounding relation to the delivery openings 46 of the coupling member 46 by a pair of end members 48 and 49. Dirt and air bubbles are removed from the oil during passage thereof through the strainer.

With the construction above described for the pumping unit 10, it will be seen that intake fluid being supplied to the intake port 29 from the reservoir chamber 35 through the supply passage 37 will be under the pressure head of the fluid in the reservoir chamber and will cause this intake port to be maintained substantially filled with fluid at all times for the rapid filling of the pumping chambers 28 therefrom.

It will also be seen from the above described arrangement of the supply passages that fluid being returned to the pump 11 through the conduit 14 from the external fluid circuit will be supplied under pressure to the branched passage 43. A portion of this returned fluid will flow upwardly through the passage 44 and through the passage 45 of the member 46 into the reservoir chamber 35. The resistance offered by the strainer.47 to the flow of this portion of the fluid into the reservoir chamber will cause a back pressure to be maintained in the passage 44 such that a portion of the returned fluid will be supplied to the other intake port 30 through the axial passage 38 of the shaft 20 under sufiicient pressure to cause the intake port 30 to be maintained substantially filled with fluid at all times for the rapid filling of the pumping chambers 28 therefrom.

The rotor means of the pump 11 is capable of delivering fluid of volume and pressure-values considerably in 4 excess of those required by the hydraulic power steering mechanism 16 of the external fluid circuit 15. It is desirable that the fluid delivered by the pump into the discharge conduit 13 be maintained at volume and pressure values which are not greatly in excess of those values actually needed by the mechanism 16, because when this is done certain desired advantages are obtained one of which is that objectionable noises, which would otherwise result from a high velocity flow of an excess volume of fluid through the external circuit 15 are prevented.

For the purpose of thus limiting the volume and pressure values of the external fluid delivery, the pump 11 is provided with by-pass means located internally thereof and which will be described next. This by-pass means comprises a volume control valve 50 located in the abovementioned valve chamber 33 and a. pressure relief valve 51 located in a valve chamber 52. This by-pass valve means is of the kind which is more fully disclosed and claimed in copending application Serial No.. 261,655 filed December 14, 1951. For the purposes of the present invention, this by-pass valve means need be only briefly described herein.

The volume control valve means, which may also be referred to as a flow control valve means, includes an internal annular valve seat 53 located in the valve chamber 33 at a point intermediate the connections of the intake and discharge ports 29 and 31 with this valve chamber. The volume control valve or so-called flow control valve 50, comprises an upper valve plunger portion 54 and a lower dash pot plunger portion 55 which are integrally connected by an axial stem 56. The dash pot plunger 55 is slidable in a dash pot cylinder 57 which is located in the valve chamber 33 at a point below the con nection of the latter with the discharge port 31. The valve plunger 54 is slidable in the valve chamber in cooperation with the valve seat 53 so as to control communication of the discharge port 31 with the intake port 29.

The valve chamber 33 is closed at its upper end by a closure plug 58 which is retained therein by a spring ring 59. This closure plug also forms a seat for a compression spring 64 which is disposed between the plug and the upper end of the valve 50. The valve member 50 as here shown is provided with a flow control orifice 61 which permits a flow of fluid from the discharge port 31 to pass through the valve member and through the upper portion of the valve chamber to the delivery conduit 13.

This flow control orifice is of a size such that it functions in cooperation with the by-pass action of the valve member 50 to permit the desired volume of fluid to be delivered to the external fluid circuit 15 through the conduit 13.- The areas of the valve member 50, which are exposed to the fluid pressure valves in the valve chamber 33 on opposite ends of the valve plunger 54, and the pressure of the spring 60 are such that the resultant effect thereof will determine the position of the valve plunger relative to the valve seat 53 such that the flow of fluid through the orifice 61 will always be of substantially the volume desired in the discharge conduit 13 and the excess volume of fluid being delivered into the discharge port 31 by the rotor means will be by-passed from the valve chamber 33 into the intake port 29 as the result of more or less opening movement of the valve plunger 54 relative to the valve seat 53.

The valve chamber 52 of the pressure relief valve means is in communication with the intake port 29 through an opening 62 and is in communication with discharge port 31 through an opening 63. At a point between the openings 62 and 63, the valve chamber 52 is provided with an internal annular shoulder forming a valve seat 64. The valve member 51 is provided with an upper valve plunger portion which is slidable in the valve chamber 52 in cooperation with the annular seat 64 and is also provided with a lower dash pot plunger portion 66 which is slidable in a dash pot cylinder 67 formed by the portion of the valve chamber which extends below the connecting opening 63.

The valve chamber 52 is closed at its upper end by a closure plug 63 which is retained in this valve chamber by a suitable spring ring 69. The closure plug 68 also forms a seat for the upper end of a compression spring 70 which is disposed between this plug and the upper end of the valve member 51.

The areas of the valve member 51 which are exposed to the pressures of the fluid in the valve chamber 52 on opposite sides of the valve seat 64 and the pressure of the spring 70 are such that the valve member 51 will function as a pressure relief valve which is responsive to the pressures of the fluid in the discharge port 31 and in the delivery conduit 13 such that the pressure in the discharge conduit will be controlled to a desired maximum value by by-passing fluid from the discharge port 31 through the valve chamber 52 to the intake port 29 in accordance with more or less opening movement of the valve plunger 65 relative to the valve seat 64.

The portion of the shaft 20 which projects through the bearing 22 also extends through and is sealed by an annular sealing device 71 which is mounted in the housing section 17 immediately adjacent to and outwardly of the annular chamber 39. The sealing device 71 is here shown as including a flexible packing 72 having a sleeve portion 72 held against the shaft by a garter spring 72 The chamber 39 serves as a leakage chamber in which any fluid leaking from the rotor chamber 19 around the shaft 20 will be collected for return to the intake side of the pump through the somewhat restricted passage 41. With the seal construction and. arrangement here shown, the fluid being supplied to the intake port 30 from the supply passage 43 will cause the leakage chamber 39 to be maintained substantially filled at all times with fluid under sufficient pressure to counteract leakage out of the rotor chamber, and to also counteract any tendency for air to leak in between the shaft 20 and the packing 72 even though a vacuum condition may he suddenly created from time to time in the intake port 30.

Figs. 8 to 13 inclusive of the drawings show a pumping unit 73 which is generally similar to the pumping unit in that it comprises a gear type pump 74 having fluid delivery and return conduits 75 and 76 connected therewith and constituting portions of an external closed-loop fluid circuit 77 and a reservoir 78 mounted directly on the pump. The close-loop external fluid circuit 77 connects the pump in operative relation with the mechanism to which the pumped fluid is to be supplied, such asa hydraulic power steering device 79 which is here shown only diagrammatically.

The pump 74 comprises a pump housing 80 formed by a housing section of body 81 containing a rotor chamber 82 and a housing section 83 connected with thehousing section 81 by means of bolts or studs 84 and forming a cover for the rotor chamber. A shaft 85 extending transversely through the rotor chamber has its inner end rotatably supported by a bushing 86 mounted in the housing section 83 and has its outer end rotatably supported by an antifriction bearing 87 mounted in a recess 88 of the housing section 81. The outer end of the shaft 85 projects beyond the bearing 87 and is adapted for connection with a rotatable driving means from which the pump 74 is to be driven.

Rotor means operable in the rotor chamber 82 and driven by the shaft 55 comprises an outer rotormember in the form of an internal gear 89 rotatably supported by a bushing 90 and an inner gear member 91 con- For supplying fluid to the rotor means so as to cause a desired rapid and substantially noiseless filling of the pumping chambers 93 in succession, the pump 74 is provided with double intake ports 94 and 95 located on opposite sides of the rotor chamber. For receiving the fluid from the pumping chambers 93, the pump 74 is also provided with discharge ports 96 and 97 located on opposite sides of the rotor chamber 82 and with which the pumping chambers come into communication in succession.

The reservoir 78 comprises a cup-shaped member 98 mounted directly on the pump housing 80 and defining a reservoir chamber 99 adapted to contain a quantity of the fluid of the pump circuit. The reservoir 78 is attached to the pump housing 80 by suitable securing means which includes a fitting 100 having a passage 101 extending therethrough and forming the inlet for a flow of fluid into the reservoir chamber. A strainer associated with the reservoir is here shown as comprising a substantially cylindrical screen 102 suitably supported in surrounding relation to the fitting 100 such that fluid entering the reservoir chamber must pass through this screen.

The pump 74 is provided with by-pass valve means of the kind which is more fully disclosed and claimed in the above-mentioned copending patent application Serial No. 261,655 and is also generally similar to the bypass valve means described above for the pump 11. This by-pass valve means comprises a volume control valve means located in a valve chamber 103 and a pressure relief valve means located in a valve chamber 104. The valve chamber 103 is in communication with the intake and discharge ports 95 and 97 through openings 105 and 106 and is provided with an internal annular valve seat 107 at a point intermediate the openings 105 and 106. The volume control valve means also includes a valve member 108 operable in the chamber 103 and having an upper valve plunger portion 109 in cooperation with the valve seat 107 and a lower dash pot plunger portion 110 slidable in a dash pot cylinder 111.

A plug 112 forms a fluid-tight closure for the upper end of the valve chamber 103 and is retained therein by a spring ring 113. The plug 112 also forms a seat for a compression spring 114 which is disposed between this plug and the upper end of the valve member 108.

A delivery passage 115 formed in the housing section 83 is in communication with the discharge port 97 through the portion of the valve chamber 103 which is located below the valve seat 107. The communication of the discharge passage 115 with the discharge port 97 is controlled by a flow control orifice 116 corresponding with the orifice 61 of the pump 11 described.

above, but the orifice 116 is here located in the pump housing instead of being, in the valve member 108 of the volume control valve means. The discharge passage 115 is also in communication with the upper portion of the valve chamber 103 through a connecting passage 117.

The valve chamber 104 of the pressure relief valve means has an annularly continuous internal valve seat or sealing surface 118 therein. At a point above this annularly continuous valve seat the valve chamber 104 is connected with the intake port 95 by a passage 119 and below this valve seat the valve chamber intersects and is in communication with the delivery passage 115. The pressure relief valve means also includes a valve member 120 operable in the valve chamber 104 and having an upper valve plunger portion 120 cooperating with the valve seat 118 and a lower dash pot plunger portion 121 operable in a dash pot cylinder 122.

The valve chamber 104 has an enlarged upper portion 104 which is closed at its upper end by a fluid-tight closure plug 123 retained therein by a spring ring 124.

The plug 123 also forms a seat for a compression spring 125 which is disposed between this plug and the upper end of the valve member 120.

The flow control valve means and the pressure relief valve means function in a similar manner to the by-pass valve means described above for the pump 11 such that the volume and pressure values of the fluid being delivered by the pump to the delivery conduit 75 will be confined substantially to values desired for the hydraulic power steering mechanism 79.

The supply passage means of the pump 74 comprises a branched passage 126 formed in the pump housing 8:) and with which the return conduit 76 communicates for supplying fluid under pressure thereto and which, in this instance, is the fluid being returned from the external fluid circuit 77. The branched passage 126 includes an upwardly extending passage portion 127 communicating with the passage 101 leading into the reservoir chamber 99. The branched passage 126 also includes a downwardly extending passage portion 128 which communicates with one of the intake ports, in this instance, the intake port 94.

A portion of the fluid returning to the pump through the conduit 75 flows upwardly through the passages 127 and 101 into the reservoir chamber 99, but in passing through the screen 102 meets suflicient resistance to cause a back pressure to occur in the passage portion 128 which extends downwardly to the intake port 94. This back pressure in the branched passage 126 causes a portion of the fluid to flow into the intake port 94 through the passage 128 for maintaining the intake port substantially filled at all times.

Fluid is supplied to the intake port 95 from the reservoir chamber 99 through a supply passage 129 formed in the housing section 83 and extending in depending relation to the reservoir chamber. The lower end of the supply passage 129 communicates with the intake port 95 through an opening 136. Fluid will thus be supplied to the intake port 95 under the pressure head of the fluid contained in the reservoir chamber 99 such that the intake port 95 will be maintained substantially filled at all times. As shown in Fig. 8, the upper portion of the valve chamber 104 of the pressure relief valve means is in communication with the supply passage 129 through a connecting passage 131 which permits the return of fluid, which leaks into the upper portion of this valve chamber, to the intake side of the pump.

As another feature of the present invention, the pump 74 is provided with novel sealing means for the shaft 85. As shown in Figs. 10 and 11, the portion of this shaft, which is mounted in the antifriction bearing 87, extends through a sealing chamber 132. A suitable packing 133 is mounted in the chamber 132 in surrounding relation to the shaft 85 and sealingly engages the latter. An annular leakage chamber 134 is formed in the housing member 81 at a point inwardly of the outer end of the sealing means, in this instance substantially at the inner end of the chamber 132. A passage 135 formed in the housing member 81 connects the leakage chamber 134 with the branched passage 126 such that the back pressure of the fluid in the latter passage will cause fluid to be supplied through the passage 135 for maintaining the leakage chamber 134 filled at ail times.

The pressure of the fluid thus maintained in the leakage chamber 134 will act to oppose the leakage of fluid out of the rotor chamber 82 and will thus enable the packing 133 to more eflectively seal the pump housing against the leakage of fluid therefrom around the shaft 85. Whatever fluid leaks out of the rotor chamber along the shaft will be collected in the leakage chamber 134 from which it will be returned to the intake side of the pump through the connecting passage 135. Since fluid is always maintained in the leakage chamber 134 under a small pressure head, the sudden occurrence of 8 a high vacuum condition in the intake port 94 will not cause air to be sucked in past the packing 133.

From the foregoing detailed description and the accompanying drawings, it will now be readily understood that this invention provides a novel construction for fluid pumps of the gear type in which double intake ports on opposite sides of the rotor means are supplied with fluid under the pressure of fluid being returned to the pump from an external circuit or under the pressure head of fluid contained in a reservoir chamber, such that these intake ports will be maintained substantially filled for a rapid and substantially noiseless filling of the pumping chambers of the rotor means. Likewise it will be seen that this invention provides novel sealing means for a rotary pump in which fluid is maintained in a leakage chamber under the pressure of the supply passage means of the pump or under the pressure head of the fluid in the reservoir chamber, such that the fluid of the leakage chamber will counteract any tendency for the leakage of fluid around the shaft from the rotor chamber.

Although the gear pumps and the pumping units of this invention have been illustrated and described herein to' a somewhat detailed extent, it will be understood of course, that the invention is not to be regarded as being limited correspondingly in scope, but includes all changes and modifications coming within the terms of the claims hereof.

Having thus described my invention, I claim:

1. In a pumping unit of the character described, a pump housing having a rotor chamber therein, rotor means comprising a pair of toothed rotors operable in said rotor chamber and having cooperating portions defining pumping chambers, a hollow shaft having drawing connection with said rotor means, said housing having discharge port means therein for receiving fluid from said pumping chambers, said housing also having a pair of substantially axially aligned intake ports therein on axially opposite sides of said rotor chamber and with which intake ports said said pumping chambers communicate in succession for a rapid filling of the individual pumping chambers by a flow of fluid thereinto from axially opposite sides of the rotor means simultaneously, supply passage means in said housing and communicating with said intake ports, and means for supplying fluid to said supply passage means under pressure suflicient to maintains said intake ports substantially filled, said supply passage means comprising connected branch passages one of which is in direct communication with one of said intake ports and another of which is in communication with the other of said intake ports through said hollow shaft.

2. In a pumping unit of the character described, a.

pump housing having a rotor chamber therein, rotor means comprising a pair of toothed rotors operable in said rotor chamber and having cooperating portions defining pumping chambers extending transversely of said rotor means, means defining a reservoir supported directly by said housing at an elevation above said rotor chamber, said housing having discharge port means therein for receiving fluid from said pumping chambers, said housing also having a pair of substantially axially aligned intake ports therein on axially opposite sides of said rotor chamber and with which intake ports said pumping chambers communicate in succession for a rapid filling of the individual pumping chambers by a flow of fluid thereinto from axially opposite sides of the rotor means simultaneously, and supply passage means including a passage connecting said reservoir with one of said intake ports for supplying reservoir fluid to the latter and branched passage means adapted to contain supply fluid under pressure and having one portion connected with said reservoir for supplying fluid thereto and another portion connected with the other of said intake ports for supplying fluid to the latter.

- 3. In apumping unit of the character described, a pump housing having a rotor chamber therein, a hollow shaft rotatable in said housing, rotor means comprising a pair of toothed rotors operable in said rotor chamber and driven by said shaft an .i having cooperating portions defining pumping chambers extending transversely of said rotor means, said housing having discharge port means therein for receiving fluid from said pumping chambers, said housing also having a pair of sub stantially axially aligned intake ports therein on axially opposite sides of said rotor chamber and with which intake ports said pumping chambers communicate in succession for a rapid filling of the individual pumping chambers from axially opposite sides of the rotor means simultaneously, means defining a reservoir chamber supported directly by said housing at an elevation above said intake ports and rotor chamber, and supply passage means including a passage connecting said reservoir chamber with one of said intake ports for supplying fluid to the latter under the head of the reservoir chamber fluid and another passage adapted to contain supply fluid under pressure and communicating with the other of said intake ports through said hollow shaft.

4. In a pump of the character described, a housing having a rotor chamber therein, a shaft rotatable in said housing and having a fluid passage therein, means defining a reservoir chamber supported directly by said housing at an elevation above said rotor chamber, rotor means comprising a pair of toothed rotors operable in said rotor chamber and driven by said shaft and having cooperating portions defining pumping chambers extending transversely of said rotor means, said housing having discharge port means therein for receiving fluid from said pumping chambers, said housing also having a pair of substantially axially aligned intake ports therein on axially opposite sides of said rotor chamber and with which intake ports said pumping chambers communicate in succession for a rapid filling of the individual pumping chambers from axially opposite sides of the rotor means simultaneously, and supply passage means including a passage leading downwardly from said reservoir chamber to one of said intake ports for supplying reservoir chamber fluid to the latter and branched passage means having one portion extending upwardly to and connected with said reservoir chamber for supplying fluid thereto and another portion connected with the other of said intake ports for supplying fluid thereto through the passage of said shaft.

5. In a pumping unit of the character described, a pump housing having a rotor chamber therein, rotor means comprising a pair of toothed rotors operable in said rotor chamber and having cooperating portions defining pumping chambers, said housing having discharge port means therein for receiving fluid from saidpurnping chambers, said housing also having a pair of substantially axially aligned intake ports therein on axially opposite sides of said rotor chamber and with which intake ports said pumping chambers communicate in succession for a rapid filling of the individual pumping chambers by a flow of fluid thereinto from axially opposite sides of the rotor means simultaneously, delivery conduit means and return conduit means connected with said housing and constituting portions of a closed-loop external fluid circuit, said delivery conduit means being in communication with said discharge port means to be supplied with pumped fluid therefrom, means defining a reservoir supported directly by said housing at an elevation above said rotor chamber, and supply passage means in said housing including a passage connecting said reservoir with one of said intake ports for supplying fluid to the latter under the head of the fluid in said reservoir and branched passage means communicating with said return conduit means to be supplied by the latter with fluid under pressure, said branched passage means including a passage portion communicating with said reservoir for returning fluid to the latter and a passage portion communicating with the other of said intake ports for supplying fluid thereto under pressure 10 suflicient to cause such other intake port to be maintained substantially filled.

6. in a pumping unit of the character described, a pump housing having a rotor chamber therein, a hollow shaft rotatable in said housing, rotor means comprising a pair of toothed rotors operable in said rotor chamber and driven by said shaft and having cooperating portions defining pumping chambers, said housing having discharge port means therein for receiving fluid from said pumping chambers, said housing also having a pair of substantially axially aligned intake ports therein on axially opposite sides of said rotor chamber and with which intake ports said pumping chambers communicate in succession for a rapid filling of the individual pumping chambers by a flow of fluid thereinto from axially opposite sides of the rotor means simultaneously, delivery conduit means and return conduit means connected with said housing and constituting portions of a closed-loop external fluid circuit, said delivery conduit means being in communication with said discharge port means to be supplied with pumped fluid therefrom, means defining a reservoir supported directly by said housing at an elevation above said rotor chamber, and supply passage means in said housing including a passage connecting said reservoir with one of said intake ports for supplying fluid to the latter under the head of the fluid in said reservoir and branched passage means communicating with said return conduit meansto be supplied by the latter with fluid under pressure, said branched passage means including a passage portion communicating with said reservoir for returning fluid to the latter and a passage portion communicating with the other of said intake ports through said hollow shaft for supplying fluid to such other intake port under pressure suflicient to cause the same to be maintained substantially filled.

7. In a pumping unit of the character described, a pump housing having a rotor chamber therein, rotor means comprising a pair of toothed rotors operable in said rotor chamber and having cooperating portions defining pumping chambers, said housing having discharge port means therein for receiving fluid from said pumping chambers, said housing also having a pair of substantially axially aligned intake ports therein on axially opposite sides of said rotor chamber and with which intake ports said pumping chambers communicate in succession for a rapid filling of the individual pumping chambers by a flow of fluid thereinto from axially opposite sides of the rotor means simultaneously, delivery conduit means and re-- turn conduit means connected with said housing and constituting portions of a closed-loop external fluid circuit, said delivery conduit means being in communication with said discharge port means to be supplied with pumped fluid therefrom, means defining a reservoir supported directly by said housing at an elevation above said rotor chamber, strainer means associated with said reservoir,

' and supply passage means in said housing including a pas sage connecting said reservoir with one of said intake ports for supplying fluid to the latter under the head of the fluid in said reservoir and branched passage means communicating with said return conduit means to be supplied therefrom with fluid under pressure, said branched passage means including a passage portion communicating with said reservoir through said strainer means for returning fluid to the reservoir and a passage portion communicating with the other of said intake ports, said strainer means offering resistance to the flow of fluid into the reservoir causing a suflicient back pressure in the last-mentioned passage portion to maintain such other intake port substantially filled.

8. in a pumping unit of the character described, a pump housing having a rotor chamber therein, a shaft rotatable in said housing, rotor means driven by said shaft and operable in said rotor chamber for producing a pumping action, said housing having intake and discharge port means therein in cooperating relation to said rotor means and including a pair of substantially axially-aligned intake ports located on axially opposite sides of said rotor means, means defining a reservoir chamber supported directly by said housing at an elevation above said rotor chamber and shaft, delivery conduit means and return conduit means connected with said housing and constituting portions of a closed-loop external circuit for pumped fluid, said delivery conduit means being in communication with said discharge port means to be supplied with pumped fluid therefrom, sealing means surrounding said shaft and including a leakage chamber located inwardly of the outer end of said sealing means, passage means in said housing for supplying fluid to one of said intake ports from said reservoir chamber, and supply passage means in said housing communicating with said return conduit means to receive fluid therefrom under pressure and including a passage portion connected with said reservoir chamber for returning fluid to the latter and another passage portion connected with the other of said intake ports and with said leakage chamber for maintaining fluid of the pressure of said supply passage means in said other intake port and leakage chamber.

9. in a pump of the character described, a housing having a rotor chamber therein, a rotatable shaft extend-- ing into said housing from one side thereof and having its inner end terminating Within said housing, rotor means driven by said shaft and operable in said rotor chamber for producing a pumping action, said shaft extending through said rotor means and having an axial fluid passage extending thereinto from said inner end toward said 12 one side of said housing and to a point beyond said rotor means, said housing having intake and discharge port means therein in cooperating relation to said rotor means and including an intake port located on the side of said rotor means nearest said one side of said housing, sealing means surrounding said shaft and including a leakage chamber located inwardly of the outer end of such sealing means, and supply passage means in said housing adapted to be supplied with fluid under pressure and communicating with said intake port through the passage of said shaft and through said leakage chamber for supplying fluid to said intake port, said leakage chamber and said intake port being maintained substantially filled with fluid under the pressure of the fluid in said supply passage means.

References Cited in the file of this patent UNITED STATES PATENTS 

